# Toward a Biomarker for Spatial Hearing Ability

> **NIH NIH F31** · UNIVERSITY OF COLORADO DENVER · 2020 · $33,287

## Abstract

Project Summary
Non-invasive measurement of electrical activity in the body has been used for over a century to assess
biological function. For example, characteristics of the electrocardiogram (ECG) are widely used to assess very
specific cardiac functions. This is possible because the mechanisms and sources of ECG waves are known.
Similarly, stimulus evoked potentials are routinely used to assess sensory function. For example, auditory
brainstem responses (ABRs) evoked by sound are used to assess function of one (monaural) or both
(binaural) ears. Distinct peaks in ABR waveforms map roughly to specific nuclei or fiber tracts in the ascending
auditory pathway and can be used to assess function at these different levels. While ABRs are widely used to
assess monaural hearing, assessment of binaural hearing remains a major clinical challenge - no routine
objective clinical measure currently exists to test for it. However, a derived component of the ABR, referred to
as the binaural interaction component (BIC), has been shown over the past decades to correlate with binaural
hearing capabilities in normal and hearing impaired listeners and thus represents a promising objective
measure of binaural function. The most prominent BIC peak, termed DN1, has been shown to be reduced (or
even absent) in populations with binaural hearing impairments including children who have experienced
temporary conductive hearing loss or been diagnosed with central auditory processing or autism spectrum
disorders, and the aged. Moreover, the amplitude and latency of DN1 vary systematically with binaural cues,
interaural time and level differences, and can predict perceived laterality of an auditory stimulus. Despite the
promise of BIC as a biomarker, in humans BIC DN1 is small and unreliably measured using typical clinical
methodology. We posit that a better understanding of the brainstem source of DN1 may provide clues to why it
is unreliably measured and also suggest avenues for more reliable measurement methods. Earlier attempts to
resolve the circuitry of the BIC using pharmacological and lesioning approaches were inconclusive. However,
several recent studies suggest that the lateral (LSO) and not the medial (MSO) superior olive of the brainstem
as a likely candidate. However, these studies are correlational and thus do not prove the LSO is the source of
the BIC. The LSO receives near-coincident excitatory and inhibitory input from the two ears which could
theoretically underlie BIC DN1. The experiments comprising Aim 1 employ a novel combination of optogenetic
and electrophysiological techniques to conclusively determine the brain region generating the BIC. Based in
part on these results, Aim 2 will determine the optimal stimulus for evoking the BIC, with the goal of reducing
variability in BIC measurements. These experiments will reveal the neural generator of the BIC DN1 and
reduce sources of variability in BIC measurements by determining the optimal stimuli to elici...

## Key facts

- **NIH application ID:** 10150454
- **Project number:** 1F31DC019291-01
- **Recipient organization:** UNIVERSITY OF COLORADO DENVER
- **Principal Investigator:** Zoe Owrutsky
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $33,287
- **Award type:** 1
- **Project period:** 2020-09-15 → 2023-09-14

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10150454

## Citation

> US National Institutes of Health, RePORTER application 10150454, Toward a Biomarker for Spatial Hearing Ability (1F31DC019291-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10150454. Licensed CC0.

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